Deep ultraviolet LEDs with a light emission wavelength of around 265 to 280 nm are expected to be used for a wide variety of applications, such as food, water purification, medical treatment, and sterilization of household electrical appliances. However, the WPE (wall-plug power conversion efficiency) of currently available products is as low as 2 to 3%. In order for deep ultraviolet LEDs to be practically used for the aforementioned applications, the WPE needs to be at least greater than or equal to 10%. This is mainly because 50% or more of deep ultraviolet light that is emitted from a quantum well is absorbed by and disappears in a p-GaN contact layer, and the light may be confined within the LED due to total internal reflection, which can then be converted into heat, and thus that the light extraction efficiency (LEE) is as low as less than 10%. Therefore, in Patent Literature 1, a photonic crystal periodic structure is formed to enhance the light extraction efficiency. Herein, it has been reported that with the method described in Non Patent Literature 1 or 2, the LEE has been improved by about 1.7 to 3 times that of a structure based on a p-GaN contact layer.